1. Field of the Invention
This invention relates to electron beam negative working resist compositions having high sensitivity.
2. Description of the Related Art
A variety of negative working resist compositions which form patterns by electron beam exposure have been proposed (e.g., Japanese Patent Laid-Open Nos. 5-249676, 9-34112 and 10-90901).
Processes for the formation of patterns using an electron beam as a light source can increase the definition of resultant patterns as compared with processes using i-line, excimer laser beams or other active rays as a light source, and the application of the former processes to the production of next-generation ultralarge scale integrated semiconductor devices of 256-megabit, 1-gigabit, 4-gigabit or higher are now under study.
Such pattern formation processes, however, use a technique of scanning an electron beam and thus imaging a mask pattern, in contrast to full wafer alignment in pattern lithography using i-line, excimer laser beams or other light sources, and required exposure time (time for imaging) and the time required for the formation of patterns increase with an increase in patterns to be imaged.
With exponentially increasing integration such as 256 megabits, 1 gigabit, 4 gigabits or higher, the time for the formation of patterns markedly increases, which may result in markedly deteriorated throughput.
Thus, the practical use of pattern formation processes using an electron beam essentially requires as short an exposure time as possible, and strong demands have been made to provide a resist composition that is a pattern forming material having satisfactorily enhanced sensitivity.